Radio astronomy is one of the most sensitive methods of astronomy in operation today. Radio astronomy employs large antennas or arrays of antennas to gather very faint radio frequency signals emitted by stars or meteors. These faint signals are then coherently combined to produce a resolvable image.
While this technique can resolve stars invisible to the human eye or even large aperture optical telescopes, radio astronomy is very susceptible to interference. Near-field competing spectrum devices such as cellular phones and other transmitters, although generally portable and low-power, produce substantially higher received power levels than cosmos-attenuated signals generated many light years away.
To combat the interference problems associated with fixed-site transmitters, radio astronomy sites are generally located in remote areas to allow attenuation of manmade interfering signals. Radio astronomy has also enjoyed restricted frequency sharing of radio astronomy bands. However, the surge in portable telephony with its frequency encroachment presents additional challenges that cannot be solved by further isolating astronomy sites.
A typical radio astronomy site combats the problems as described above by disallowing the transmission of potentially interfering signals within a prescribed boundary. This prevention technique breaks down, however, as portable transmitters become more powerful and utilize additional frequency spectrum.
One solution known in the prior art is to generate a local beacon signal at the radio astronomy site. This local beacon emits a receivable signal throughout the vicinity of the radio astronomy site. This solution is bulky and expensive because of the additional special receiver required to detect a special beacon signal.
Thus, what is needed is a beacon system capable of providing beacon protection near a radio astronomy site, but not requiring special receivers.
Also, what is needed is a low-cost, effective method of providing beacon protection to a radio astronomy site that does not require additional subscriber unit receiver circuitry.